Compressor Unit

ABSTRACT

A compressor unit has a motor and a reciprocating-piston compressor which is driven via a slider-crank drive. The slider-crank drive includes a crank wheel and a connecting rod, which is connected to the crank wheel and a piston. The piston stroke can be adjusted by a threaded connection that allows an exact spacing between the crank drive and the piston to be set.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuing application, under 35 U.S.C. § 120, of copending international application No. PCT/EP2006/068011, filed Nov. 1, 2006, which designated the United States; this application also claims the priority, under 35 U.S.C. § 119, of German patent application DE 10 2005 060 320.3, filed Dec. 16, 2005; the prior applications are herewith incorporated by reference in their entirety.

BACKGROUND OF THE INVENTION Field of the Invention

The invention relates to a compressor unit, in particular for air compression within portable/transportable appliances. The compressor unit has at least one motor and a reciprocating piston compressor driven via a slider crank mechanism. The slider crank mechanism consists of a crank wheel and a connecting rod connected to the crank wheel and to a piston.

In such piston compressors, in particular in very simple piston compressors that are produced in large quantities, such as, for example, small compressors for the filling of tires, it is desirable to keep the maximum pressure within specific limits, so that, on the one hand, no material overload occurs on the compressor components or a high compressor power and service life can be achieved, along with an economical use of material, and, on the other hand, pressure filling takes place only up to a maximum pressure without further costly regulating devices.

To set the maximum pressure in the working space of the piston compressor, there are some known methods whereby a volumetric displacement setting and therefore a pressure setting can be carried out by a variation in the dead air volume. What is in this context designated as dead air volume or also as “harmful volume” is that part of the cylinder volume, delimited by the piston head and the cylinder walls, which still remains between the piston head and cylinder wall after the completion of the compression stroke.

These methods include, for example, the assembling of the components—to be precise, the piston, the connecting rod, the cylinder, and the cylinder head—with correspondingly suitable tolerances. This, however, can be carried out successfully only in the case of a sufficiently accurate production of the individual parts and even then remains a costly compromise.

A further method is to introduce cylinder head gaskets of differing thickness, by means of which the dead air volume can likewise be influenced. However, this is basically a labor-intensive and merely gradual approximation to the correct pressure conditions.

A further solution is pressure relief valves in the piston head or in the cylinder walls, said valves opening at a maximum pressure. Apart from the additional components required, in this solution the pressure pulses and the generation of noise occasionally present problems.

German published patent application DE 10 2004 015 618 A1 discloses an axial piston compressor with a variable and regulatable volumetric displacement, in which essentially the pressure in the engine chamber can be regulated (closed-loop controlled) in real time by one or more regulating valves. What is in that context designated as the engine chamber or else “regulation volume” is the space in which the piston drive mechanism is arranged. Regulation takes place with the aid of an algorithm taking into account one or more operating parameters, and the regulating valves are arranged such that the engine chamber can be connected either to the suction side and/or to the high-pressure side.

This is intended primarily to prevent icing-up which could occur due to an excessive lowering of the pressure on the suction side. In the case of simple and small axial piston compressors in which the intake air flows through the piston drive housing of the compressor, that is to say in which the low-pressure or suction side and the engine chamber coincide, such complicated regulation cannot be implemented.

Moreover, in the powers of small compressors, icing-up on the low-pressure side is less important than to limit the maximum pressure on the high-pressure side, in order either to achieve better material utilizations or else make manufacturing tolerances capable of being handled for large series manufacture.

BRIEF SUMMARY OF THE INVENTION

It is accordingly an object of the invention to provide a compressor unit which overcomes the above-mentioned disadvantages of the heretofore-known devices and methods of this general type and which provides for a compressor construction which allows a highly accurate setting of the maximum pressure without high outlay independently of types of manufacture and manufacturing tolerances, so that the reworking of components is avoided.

With the foregoing and other objects in view there is provided, in accordance with the invention, a compressor unit, comprising:

at least one motor;

a reciprocating piston compressor with a piston having a given piston stroke;

a slider crank mechanism connected for driving the reciprocating piston compressor, the slider crank mechanism including a crank wheel, a connecting rod connected between the crank wheel and the piston, and a threaded connection for adjusting the piston stroke within the slider crank mechanism.

In other words, the objects of the invention are achieved in that means for adjusting the piston stroke is arranged within the slider crank mechanism which consists of a crank wheel and of a connecting rod connected to the crank wheel and to a piston. By virtue of such a design, the piston stroke and consequently the remaining dead air volume and the maximum pressure can be set in the simplest possible way during assembly, with the remaining dimensions and tolerances being given.

In an advantageous design, a connection adjustable in length in the sliding direction is arranged between the piston and connecting rod.

By virtue of such a design, during the assembly of the compressor, the remaining dead air volume and consequently the maximum pressure can be set, in the case of given tolerances, simply by shortening or lengthening the distance between the piston head and articulation point of the connection rod on the crank wheel.

This also makes it possible to have a cost-effective large series production of the components by means of shaping casting methods, such as, for example, by means of a diecasting method, without the customary comprehensive reworking for maintaining all the tolerances being required.

As noted, in the preferred construction, the piston and the connecting rod are connected to one another by means of a threaded connection. In addition, the threaded connection preferably has an antitwist device. Consequently, a functional separation in length setting as such and in the fixing of the length setting can be achieved in a simple way.

In a further design which is particularly simple and cost-effective to implement, the antitwist device is obtained by means of a headless screw which engages into the thread and which has a rear tool catch. Readjustment, for example after test runs, is readily possible here.

Particularly good settability is obtained in a design in which the threaded connection is designed as a fine thread.

In a further advantageous design, there is arranged between the motor and piston compressor a gear unit which has essentially the slider crank mechanism and at least one gearwheel stage as a gear stage. As a result, particularly in low-voltage systems, motors with a higher rotational speed which then have a corresponding reduction can be used.

Such a compressor is particularly suitable within a device for sealing off and pumping up inflatable articles, in particular for sealing off and pumping up of motor vehicle tires, the device containing, furthermore, a container for an automatic sealing means introducible into the inflatable article, a valve and distributor unit for sealing means and compressed gas, with an inlet line connectable to the compressor and with an outlet line connectable to the inflatable article, connection means between the valve and distributor unit and inflatable article, if appropriate connection means for energy supply, and also switching and/or control and indicator means for operating the device. In such a device, the maximum pressure of the piston compressor is then preferably limited to a value of 6 to 8 bar, preferably to a value of 7 bar, with the aid of the means for adjusting the piston stroke. The advantage of such a version is that, here, repair sets manufactured from completely identical individual parts are provided, which are tailored specially to a vehicle or to a vehicle tire size and the corresponding air pressure range and which can be set to a specific vehicle type by the simplest possible measures merely by varying their maximum pressure.

Other features which are considered as characteristic for the invention are set forth in the appended claims.

Although the invention is illustrated and described herein as embodied in compressor unit, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.

The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1 is a basic diagram showing a compressor unit according to the invention;

FIG. 2 is a side view of an implementation of an embodiment of a compressor unit according to the invention; and

FIG. 3 is a diagrammatic view of a self-contained compressor system for sealing and inflating a tire.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the figures of the drawing in detail and first, particularly, to FIG. 1 thereof, the compressor unit 1 according to the invention, in its basic diagrammatic layout, a piston compressor 2, and also a gear unit 3. The gear unit 3 comprises, on the output side, a slider crank mechanism 4. The latter, to be more precise, includes a crank wheel 5 and of an articulated connecting rod 6 as a coupling member to a sliding member 7.

Between the electric motor 8, which is used as a drive, and the slider crank mechanism 4, there is disposed a gearwheel stage forming a gear stage 9 for the reduction of the motor rotational speed. The gear stage is connected in the gear unit 3 downstream of the motor in the force flux direction.

FIG. 2 shows a version of a compressor unit 1 according to the invention in two views, rotated by 90° with respect to one another. The compressor unit 1, here, is likewise equipped with a piston compressor 2 of very short build and with a gear unit 3 which comprises, on the output side, a slider crank mechanism 4. The latter consists of a crank wheel 5 and of an articulated connecting rod 6 as a coupling member to the sliding member 7, designed as a piston. The piston reciprocates between top dead center (TDC) and bottom dead center (BDC).

Here, too, between the electric motor 8 used as a drive and the slider crank mechanism 4, a gear stage 9 for the reduction of the motor rotational speed is arranged in the force flux direction.

The piston or the sliding member 7 is connected to the connecting rod 6 with the aid of a fine-thread connection 10. After setting has taken place, the fine-thread connection 10 can be tightened or locked with the aid of a headless screw 11, such as a setting screw with an hexagon wrench socket or Allen wrench head, so as to secure the fine thread connection against twisting. The term “fine thread” should be understood in the context as being a thread connection with a very low rise so that the connection allows very fine volume adjustments, i.e., fine adjustments of the spacing between the rotary axis of the crank and the piston.

The dead air volume 12 is in this case gradually, infinitely, and very accurately set by way of the fine-thread connection 10. The dead air volume (i.e., the cylinder free volume at TDC) is directly proportional to the maximum pressure due to the degree of compression which arises.

FIG. 3 shows, in a highly diagrammatic illustration, a compressor system for sealing and inflating inflatable articles. Here, the article is a motor vehicle tire. The system includes the compressor unit 1, as described in the foregoing. The compressor unit 1 is connected via a valve 13 to a valve and distributor unit 14 for sealant and compressed gas. The unit 14 is connected to a container 15 via a connecting line 16. The container contains sealant, i.e., a sealing agent or sealing means. The valve and distributor unit 14 is further connected to an outlet line 17, which may be connected to a tire valve of a tire 18. It will be understood that the self-contained system of FIG. 3 may be disposed in a unitary, portable housing.

The compressor unit 1, i.e., the piston compressor of this system, is preferably set to a maximum pressure of about 6 to 8 bar (87 to 116 psi), and preferably to a pressure value of 7 bar (˜100 psi). The setting is easily and exactly attained by the length-adjustable connecting rod. 

1. A compressor unit, comprising: at least one motor; a reciprocating piston compressor with a piston having a given piston stroke; a slider crank mechanism connected for driving said reciprocating piston compressor, said slider crank mechanism including a crank wheel, a connecting rod connected between said crank wheel and said piston, and a threaded connection for adjusting the piston stroke within said slider crank mechanism.
 2. The compressor unit according to claim 1, wherein said threaded connection is disposed to enable a length adjustment of said connecting rod.
 3. The compressor unit according to claim 1, configured in a portable compressor unit.
 4. The compressor unit according to claim 1, configured in a mobile and transportable appliance.
 5. The compressor unit according to claim 1, which comprises an antitwist device for locking said threaded connection.
 6. The compressor unit according to claim 5, wherein said antitwist device is a headless screw engaging into a thread of the threaded connection and having a rear tool catch.
 7. The compressor unit according to claim 1, wherein said threaded connection is a fine thread.
 8. The compressor unit according to claim 1, which comprises a gear unit connected between said motor and said piston compressor, said gear unit including said slider crank mechanism and at least one gearwheel stage.
 9. The compressor system for sealing and inflating inflatable articles, comprising: a compressor unit according to claim 1; a container for an automatic sealing means for introduction into and sealing the inflatable article; a valve and distributor unit for the sealing means and compressed gas, and a valve connecting said distributor unit with said compressor unit; and an inlet line connecting said valve and distributor unit to said container for the sealing means and an outlet line for connecting said valve and distributor unit to an inflatable article; and wherein a maximum pressure of said compressor unit is set to approximately 6 to 8 bars by setting said threaded connection.
 10. The compressor system according to claim 9, wherein the maximum pressure is set to a value of 7 bar.
 11. The compressor system according to claim 9, wherein the inflatable article is a motor vehicle tire. 